Traditionally managed landscapes do not prevent amphibian decline and the extinction of paedomorphosis

Abstract

Eco‐cultural landscapes are assumed to be favorable environments for the persistence of biodiversity, but global change may affect differently their terrestrial and aquatic components. Few long‐term studies have examined how multiple, global change stressors may affect wetland biodiversity in such environments. Facultative paedomorphosis is a spectacular example of intra‐specific variation, in which biphasic (metamorphosing) amphibians coexist with fully aquatic conspecifics that do not metamorphose (paedomorphs). Paedomorphosis is seriously threatened by global change stressors, but it is unknown to what extent traditional management will allow its long‐term persistence. Here, we tested the effects of alien species introductions while taking into account land use and climate changes on the distribution of two polymorphic newt species (Ichthyosaura alpestris and Lissotriton graecus) in Montenegro by using a 68‐yr data set and Bayesian mixed models integrating complex spatial and temporal structures. We found that, despite the persistence of natural landscapes, metamorphs dramatically declined and paedomorphs were nearly extirpated, losing 99.9% of their aquatic area of occupancy and all the major populations. Fish introduction was the main determinant of decline for both phenotypes. Climate and the presence of crayfish further contributed to the decline of metamorphs, which started later and was less dramatic than that of paedomorphs. The near extinction of paedomorphosis on a country‐wide scale shows how invasive species determine broad‐scale impacts, which can be even stronger than other global change stressors, and underlines the need for immediate management actions to avoid the extinction of a unique developmental process, paedomorphosis.

Reproductive fitness consequences of progenesis: Sex‐specific pay‐offs in safe and risky environments

“…Specifically, paedomorphic newts and salamanders could be used to test how developmental changes impact individual success (see also Whiteman, ) and how it relates to global change (Bonett, Steffen, Lambert, Wiens, & Chippindale, ). This is timely as new anthropogenic pressures, such as climate change and massive introduction of invasive species, are threatening the last remaining populations of paedomorphic newts and salamanders across the globe (Denoël, Ficetola, et al., ; Turvey et al., ; Voss, Woodcock, & Zambrano, ; Walls, Barichivich, Brown, Scott, & Hossack, ).…”

First limnological characterization of Lakes Leqinat and Drelaj in Bjeshkët e Nemuna National Park, Kosovo

“…Higher densities have been reported for similar-sized lakes in northern Greece (Denoël & Schabetsberger 2003; > 30 000 individuals), but these included a large proportion of paedomorphic individuals. Hridsko Jezero from the Montenegrin part of the mountain range also used to host a population of paedomorphs (Denoël et al 2001), but now only metamorphosed individuals occur (Denoël et al 2019). In Leqinat, the sex ratio was slightly biased towards males (0.62).…”

“…Indeed, many major populations of alpine newts that inhabited mountain lakes in the Balkans, even within National Parks, have now vanished because of fish introductions. Such introductions were particularly detrimental in Montenegro, including in Hridsko Jezero, where fortunately fish have recently disappeared (Denoël et al 2019). Although we are not aware of any immediate stocking campaigns, hydropower development in the Rugova Valley is an issue and may be associated with stocking campaigns in the region (personal observation).…”

“…Larval structures, such as gills and gill slits, are retained in adult animals. Many paedomorphic populations have become extinct in the Balkans, including all larger populations from Montenegro (Denoël et al 2005(Denoël et al , 2019. The loss of this intraspecific heterochrony represents a massive loss to diversity and there is an urgent need for better conservation of the remaining populations.…”

A co‐development approach to conservation leads to informed habitat design and rapid establishment of amphibian communities

“…The decline of amphibians is a major global biodiversity concern and has been linked to anthropogenic drivers including habitat loss, land use change, pollution, over‐exploitation, disease and invasive species (Beebee & Griffiths, 2005; Scroggie et al., 2019), often acting in combination. Remediation of such threats can be particularly challenging outside of protected areas such as in places primarily managed for economic purposes (Denoël et al., 2019; Hartel, Scheele, Rozylowicz, Horcea‐Milcu, & Cogălniceanu, 2020). Indeed, land managed for forestry and agriculture, rather than for conservation per se , comprises a greater proportion of rural land globally and provides vital habitat for many species (e.g.…”